I'd not seen this before but it doesn't surprise me, I guess other manufacturers will follow. As far as I can see the plate heat exchanger/water heater bit is simply another spur off a multi split system and like A/A itself is well tried and tested but would require an " F " gas fitter to install; no harm in that.
I think I once heard that remote plate heat exchangers have always been possible as part of a heat pump set and it surprises me that the concept isn't more widely adopted, better in many ways than monobloc IMO.

Interesting, but ... in a poor-to-averagely insulated house, requiring a lot of heat input relative to available heat-emitter area, hence heat emitters running at higher temp, hence higher air-to-water heat pump output temp, hence degraded CoP, the latest type of heat pump using CO2 as refrigerant can apparently maintain better CoP under such conditions. Alternatively an air-to-air heat pump can deliver its output at exactly target room-air temp, just a lot of it, i.e. cooler than any air-to-water heat pump, whether in a well-insulated or a poor-to-averagely insulated house, hence potentially best-of-all CoP. That depends upon delivering its output as warm air, not as warmer (or hot) water.

So, getting to the point, I don't see Will's idea of using refrigerant-filled heat emitters, whether as exposed radiant-plus-convective emitters (like an ordinary 'radiator'), or embedded in floor (or wall?) screed (like UFH). Either way, HP's output wd have to be at (a little or a lot) higher temp than an air-to-air setup, so back to degraded CoP - innit?

Or is it that the stage that causes the degradation of CoP is the heat transfer between refrigerant and intermediate emitter-thermofluid (water) or via fan-coil to air? In which case using the refigerant directly as emitter-thermofluid could be advantageous enough to overcome the CoP degradation due to required higher HP output temp? Or reduce the required HP output temp?

Hi Tom, as your last paragraph. The issue with Air-water heat pumps is the heat needs to get transferred twice, once from the refrigerant to the CH water, then again from the CH water to the air or DHW. Whereas air-air heatpumps only have one heat transfer step.

Each transfer needs some delta T, twice as much for the A-W as the A-A, so the refrigerant needs to run hotter in an A-W than it does in an A-A. Hence the generally poorer CoP.

An air-air hp directly heating a big radiator or UFH or DHW cylinder, would be as efficient as an air-air heating a fan unit (a fan unit is basically a little radiator with a fan).

As you know the advantage of radiant heating is it makes people feel warmer even at lower temperatures, so is more economical than the purely convective heat transfer you get out of an a-a fan unit.

Hi Owlman, the radiator can have lots of flow loops in parallel (like a conventional UFH) to limit the pipe length, if required.

<blockquote><cite>Posted By: WillInAberdeen</cite>

Hi Owlman, the radiator can have lots of flow loops in parallel (like a conventional UFH) to limit the pipe length, if required.</blockquote>



Hi Will,
Multi split units are governed by their initial design and therefore the number of splits they can accommodate, each with their total design length. That I can assume is governed by compressor pump size and capacity. I can also imagine that any form of radiant heat emitter will quickly exceed that design criterion. it may be possible to have bigger and bigger units to facilitate the many " refrigerant flow loops " you envisage, but in reality more industrial than domestic, no?
Even then one sees commercial units racked up in rows, rather than one large unit.

Posted By: djhI just replaced a radiant heater in our shower with a fan heater of marginally lower power. We both find the fan is better (more comfortable)

That goes against all that I've understood - and experienced! How come?

Ah - so the solution might be to place the radiant heater so it can 'see' the body in the shower - toasty!

A wonderful system. And if I installed it, my EPC would worsen. Madness.

Re: OP & Bogal2 here is a similar thing from Toshiba.

https://www.toshiba-aircon.co.uk/product/r410a-estia-5-series-air-to-water-split-heat-pump-system/

Apologies, I got it wrong.

I wrongly thought that because the indoor and outdoor units are refrigerant connected, ( not water as in monobloc ), I assumed the fan coil emitters for both heating and cooling were refrigerant types. They do come off a water space heating circuit though.
I'm not sure if Toshiba twin R32 units have two sets of refrigerant outlets where maybe you could run one with the ESTIA water heater and the other as A/A. Alternatively just an independent stacked double.

Nice project!

https://www.cibsejournal.com/case-studies/digging-for-britain-swaffham-priors-heat-network/ (no paywall)

"The heat network is designed to supply heat at around 72°C, in line with that generated by oil-fired central heating.The high temperature will enable residents to dispense with conventional oil-fired boilers... without having to upgrade radiators or insulation."

"heat pumps with ammonia as the refrigerant [are] able to generate higher temperatures while maintaining a reasonably good COP"

"connected to a 28MW (AC)/39MW (DC) solar farm"

"two 0.75MW GSHPs and one 0.5MW ASHP.... using the ASHP in the summer, as the warmer air gives a higher coefficient of performance... gives the GSHPs’ ground loops a chance to replenish"


"1.5MW ... immersion heaters as the back-up heat source... 4x50m³ thermal stores"

"£11.9m capital cost.... 300 homes – as well as two churches, a pub and school"
[IE £40k capital cost per house served]

Posted By: GarethCIsn't ammonia fairly toxic stuff??

Yes, and can also explode in the right conditions But the article Will linked to explains the precautions in the energy centre. What I'm not clear about is what fluid is distributed in the heat mains to the individual units at the houses. Is that just plain water? A hot water main?

Apart from the two individuals in the village who drove the idea, they seem to have been very lucky with the local councils who had the spare land and nearby solar farm that make the whole thing economically viable.

I'm not sure how many of the 300 houses the project can serve. 1.5 MW / 300 houses = 5 kW per house. Given that the houses haven't been adapted, is that likely to be enough power on a cold day? If it was half that number then the capital cost would double per house of course.

Posted By: Peter_in_Hungary£40k is an awful lot of money to swap out a gas boiler !

Good point. It would pay for a good amount of insulation instead.

Posted By: VictorianecoWe have air to air in our office and my wife's shop. Don't think we'd like to use it in a house.

We get 2mins of freezing cold air almost every hour

I'm curious to know who is the manufacturer of the units.

They'll be the electriQ ones I guess.

I mentioned Victorianeco's comments to my "F " Gas fitter ( 30 years experience ), fitting commercial, industrial, and domestic Aircon, and still doing so.
It was something he had never experienced. He can only think it's defective equipment, or controls, assuming of course that the install was correct, and done by an experienced fitter.

1. The indoor unit temperature settings may be incorrect.
2. The indoor unit temperature sensor may be defective
3. The indoor unit fan may be defective
4. The outdoor unit defrost cycle is not operating correctly, or it may be badly sited, causing it to do so.

The installer needs calling to rectify the problem. Reverse Cycle heat-pumps are generally problem free, and it may only require the controls tweaking.
As a rule my fitter only fits branded equipment from the major manufacturers with good service and spares backup, and good control systems.